cidr

问题 I was in the process of creating a new AWS VPC for my instances. However, I noticed that when I used CIDR Notation to create the VPC & Public Subnet, AWS indicates that I have n^2 - 4 (where n is the # of bits) available IP addresses? Why is this? I understand that when n^2 -2 occurs it is usually to remove the case where bits are all 0s or all 1s. But am not sure why it is - 4 in this case. Here the /28 indicates 11 IP addresses available when I expected 15 or 13, and 251 when I expected 255

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed last year . Does anyone know of an API / Script which gives me the CIDR for the network of an IP address? Not IP-Range to CIDR! Background: A fraudster registers on my site and use a proxy or a web hoster to hide his IP address or to fake his ip position. Now it makes little sense to just block his IP address. I want to lock

问题 How to detect if there is intersection between two Golang net.IPNet objects? That is, how to check both if the first network is subnet of the second one OR if the second network is subnet of the first one. Does Go provide any utility function ready for this specific task? See test code below. package main import ( "fmt" "net" ) func main() { _, net1, _ := net.ParseCIDR("1.1.1.1/24") _, net2, _ := net.ParseCIDR("1.1.0.2/16") _, net3, _ := net.ParseCIDR("1.1.1.3/25") _, net4, _ := net.ParseCIDR

问题 How to detect if there is intersection between two Golang net.IPNet objects? That is, how to check both if the first network is subnet of the second one OR if the second network is subnet of the first one. Does Go provide any utility function ready for this specific task? See test code below. package main import ( "fmt" "net" ) func main() { _, net1, _ := net.ParseCIDR("1.1.1.1/24") _, net2, _ := net.ParseCIDR("1.1.0.2/16") _, net3, _ := net.ParseCIDR("1.1.1.3/25") _, net4, _ := net.ParseCIDR

问题 How can I convert a ipv4 subnet mask to cidr notation using netaddr library? Example: 255.255.255.0 to /24 回答1: Using netaddr: >>> from netaddr import IPAddress >>> IPAddress('255.255.255.0').netmask_bits() 24 Using ipaddress from stdlib: >>> from ipaddress import IPv4Network >>> IPv4Network('0.0.0.0/255.255.255.0').prefixlen 24 You can also do it without using any libraries: just count 1-bits in the binary representation of the netmask: >>> netmask = '255.255.255.0' >>> sum(bin(int(x)).count

问题 How can I convert a CIDR prefix to a dotted-quad netmask in Python? For example, if the prefix is 12 I need to return 255.240.0.0 . 回答1: You can do it like this: def cidr(prefix): return socket.inet_ntoa(struct.pack(">I", (0xffffffff << (32 - prefix)) & 0xffffffff)) 回答2: Here is a solution on the lighter side (no module dependencies): netmask = '.'.join([str((0xffffffff << (32 - len) >> i) & 0xff) for i in [24, 16, 8, 0]]) 回答3: And this is a more efficient one: netmask = 0xFFFFFFFF & (2**(32

问题 I want to do two things: Convert IP Address inputs into CIDR Here are some example inputs: 1.1.1.1 192.168.*.* #=> 192.168.0-255.0-255 192.168.1.2-20 1.1.1-10.1-100 Check if a given IP Address falls into any CIDR. This must be a very fast query, as it's a very common lookup in my web app. I'm thinking of doing something like this: def matches?(request) valid = @ips.select {|cidr| cidr.contains?(request.remote_ip) } !valid.empty? end I think converting IP ranges into CIDR will let lookups be

问题 I am having trouble with some of the logic in converting an IP Address range into a list of CIDR blocks. I do believe that this website is doing it right: http://ip2cidr.com/ I would like to pass in a starting IP address and an ending IP address and have the java spit out the minimum list of CIDR blocks required to cover only the range passed in and nothing more. For instance, if I pass in a start address of 1.1.1.111 and an end address of 1.1.1.120, I would expect to get in return: 1.1.1.111

问题 I have been handed the task of creating a function in python (3.1) that will take a CIDR notation and return the list of possible ip addresses. I have looked around python.org and found this: http://docs.python.org/dev/py3k/library/ipaddr.html but i haven't seen anything that will fill this need... I would be very grateful for any assistance anyone cares to kick my way. thanks in advance. :-) 回答1: If you aren't married to using the built-in module, there is a project called netaddr that is

问题 Something like SELECT COUNT(*) AS c FROM BANS WHERE typeid=6 AND (SELECT ipaddr,cidr FROM BANS) MATCH AGAINST 'this_ip'; So you don't first fetch all records from DB and then match them one-by one. If c > 0 then were matched. BANS table: id int auto incr PK typeid TINYINT (1=hostname, 4=ipv4, 6=ipv6) ipaddr BINARY(128) cidr INT host VARCHAR(255) DB: MySQL 5 IP and IPv type (4 or 6) is known when querying. IP is for example ::1 in binary format BANNED IP is for example ::1/64 回答1: Remember